Unable to load memcache.so extension

I built PHP from source with configure command

'./configure' '--prefix=/usr/local/php-5.2.8' '--with-config-file-path=/etc --with-config-file-scan-dir=/etc/php.d' '--with-apxs2=/usr/local/httpd/bin/apxs' '--with-mysql=/usr/local/mysql/' '--with-zlib' 

I installed php memcache extension :

wget http://pecl.php.net/get/memcache
tar -zxvf memcache-2.2.5.tgz
cd memcache-2.2.5
phpize
./configure --enable-memcache
make
make install

I add to my /usr/local/lib/php.in

extension=memcache.so

Rebooted my apache and run php-m but php seem doesn't load memcache extension
I followed this solution from this site
http://www.howtoforge.com/forums/showthread.php?t=26554

I added full path

extension=/usr/local/lib/php/extensions/no-debug-non-zts-20060613/memcache.so 

rebooted apache
But it didn't load memcache extension ! I google around but the same issue !
How can I load this extension _ _"